Currently, Google allows up to 100 refresh tokens per Google account per OAuth client. Each time a Google integration is authorized, a new refresh token is generated. This means if you're using one account across 100 instances, then create a 101st and the very first added will stop working properly. The total number of instances includes: Google Sheets, Google Drive, Google Calendar, and Google Contacts.
Example: If you're using 5 forms and have set up each of those 4 integrations on every one of them, the total number of instances on the Google login would be 20 (5 x 4).
Having more than 100 instances will cause some of the instances to stop working. With Google Drive, this can be seen when folders don't load properly in the integration settings. Google Sheets might not load spreadsheets properly when added.
There are two ways to work around this restriction. One is to isolate what forms in your account need to use the Google integrations and avoid using them on additional forms. The other is to use multiple Google logins to set up Google integrations on your forms.
Note: Google recommends 15–20 as the number of clients to authorize per account.